1/*
2 *  include/linux/ktime.h
3 *
4 *  ktime_t - nanosecond-resolution time format.
5 *
6 *   Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
7 *   Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
8 *
9 *  data type definitions, declarations, prototypes and macros.
10 *
11 *  Started by: Thomas Gleixner and Ingo Molnar
12 *
13 *  Credits:
14 *
15 *  	Roman Zippel provided the ideas and primary code snippets of
16 *  	the ktime_t union and further simplifications of the original
17 *  	code.
18 *
19 *  For licencing details see kernel-base/COPYING
20 */
21#ifndef _LINUX_KTIME_H
22#define _LINUX_KTIME_H
23
24#include <linux/time.h>
25#include <linux/jiffies.h>
26
27/*
28 * ktime_t:
29 *
30 * On 64-bit CPUs a single 64-bit variable is used to store the hrtimers
31 * internal representation of time values in scalar nanoseconds. The
32 * design plays out best on 64-bit CPUs, where most conversions are
33 * NOPs and most arithmetic ktime_t operations are plain arithmetic
34 * operations.
35 *
36 * On 32-bit CPUs an optimized representation of the timespec structure
37 * is used to avoid expensive conversions from and to timespecs. The
38 * endian-aware order of the tv struct members is choosen to allow
39 * mathematical operations on the tv64 member of the union too, which
40 * for certain operations produces better code.
41 *
42 * For architectures with efficient support for 64/32-bit conversions the
43 * plain scalar nanosecond based representation can be selected by the
44 * config switch CONFIG_KTIME_SCALAR.
45 */
46typedef union {
47	s64	tv64;
48#if BITS_PER_LONG != 64 && !defined(CONFIG_KTIME_SCALAR)
49	struct {
50# ifdef __BIG_ENDIAN
51	s32	sec, nsec;
52# else
53	s32	nsec, sec;
54# endif
55	} tv;
56#endif
57} ktime_t;
58
59#define KTIME_MAX			((s64)~((u64)1 << 63))
60#define KTIME_SEC_MAX			(KTIME_MAX / NSEC_PER_SEC)
61
62/*
63 * ktime_t definitions when using the 64-bit scalar representation:
64 */
65
66#if (BITS_PER_LONG == 64) || defined(CONFIG_KTIME_SCALAR)
67
68/**
69 * ktime_set - Set a ktime_t variable from a seconds/nanoseconds value
70 * @secs:	seconds to set
71 * @nsecs:	nanoseconds to set
72 *
73 * Return the ktime_t representation of the value
74 */
75static inline ktime_t ktime_set(const long secs, const unsigned long nsecs)
76{
77#if (BITS_PER_LONG == 64)
78	if (unlikely(secs >= KTIME_SEC_MAX))
79		return (ktime_t){ .tv64 = KTIME_MAX };
80#endif
81	return (ktime_t) { .tv64 = (s64)secs * NSEC_PER_SEC + (s64)nsecs };
82}
83
84/* Subtract two ktime_t variables. rem = lhs -rhs: */
85#define ktime_sub(lhs, rhs) \
86		({ (ktime_t){ .tv64 = (lhs).tv64 - (rhs).tv64 }; })
87
88/* Add two ktime_t variables. res = lhs + rhs: */
89#define ktime_add(lhs, rhs) \
90		({ (ktime_t){ .tv64 = (lhs).tv64 + (rhs).tv64 }; })
91
92/*
93 * Add a ktime_t variable and a scalar nanosecond value.
94 * res = kt + nsval:
95 */
96#define ktime_add_ns(kt, nsval) \
97		({ (ktime_t){ .tv64 = (kt).tv64 + (nsval) }; })
98
99/* convert a timespec to ktime_t format: */
100static inline ktime_t timespec_to_ktime(struct timespec ts)
101{
102	return ktime_set(ts.tv_sec, ts.tv_nsec);
103}
104
105/* convert a timeval to ktime_t format: */
106static inline ktime_t timeval_to_ktime(struct timeval tv)
107{
108	return ktime_set(tv.tv_sec, tv.tv_usec * NSEC_PER_USEC);
109}
110
111/* Map the ktime_t to timespec conversion to ns_to_timespec function */
112#define ktime_to_timespec(kt)		ns_to_timespec((kt).tv64)
113
114/* Map the ktime_t to timeval conversion to ns_to_timeval function */
115#define ktime_to_timeval(kt)		ns_to_timeval((kt).tv64)
116
117/* Convert ktime_t to nanoseconds - NOP in the scalar storage format: */
118#define ktime_to_ns(kt)			((kt).tv64)
119
120#else
121
122/*
123 * Helper macros/inlines to get the ktime_t math right in the timespec
124 * representation. The macros are sometimes ugly - their actual use is
125 * pretty okay-ish, given the circumstances. We do all this for
126 * performance reasons. The pure scalar nsec_t based code was nice and
127 * simple, but created too many 64-bit / 32-bit conversions and divisions.
128 *
129 * Be especially aware that negative values are represented in a way
130 * that the tv.sec field is negative and the tv.nsec field is greater
131 * or equal to zero but less than nanoseconds per second. This is the
132 * same representation which is used by timespecs.
133 *
134 *   tv.sec < 0 and 0 >= tv.nsec < NSEC_PER_SEC
135 */
136
137/* Set a ktime_t variable to a value in sec/nsec representation: */
138static inline ktime_t ktime_set(const long secs, const unsigned long nsecs)
139{
140	return (ktime_t) { .tv = { .sec = secs, .nsec = nsecs } };
141}
142
143/**
144 * ktime_sub - subtract two ktime_t variables
145 * @lhs:	minuend
146 * @rhs:	subtrahend
147 *
148 * Returns the remainder of the substraction
149 */
150static inline ktime_t ktime_sub(const ktime_t lhs, const ktime_t rhs)
151{
152	ktime_t res;
153
154	res.tv64 = lhs.tv64 - rhs.tv64;
155	if (res.tv.nsec < 0)
156		res.tv.nsec += NSEC_PER_SEC;
157
158	return res;
159}
160
161/**
162 * ktime_add - add two ktime_t variables
163 * @add1:	addend1
164 * @add2:	addend2
165 *
166 * Returns the sum of addend1 and addend2
167 */
168static inline ktime_t ktime_add(const ktime_t add1, const ktime_t add2)
169{
170	ktime_t res;
171
172	res.tv64 = add1.tv64 + add2.tv64;
173	/*
174	 * performance trick: the (u32) -NSEC gives 0x00000000Fxxxxxxx
175	 * so we subtract NSEC_PER_SEC and add 1 to the upper 32 bit.
176	 *
177	 * it's equivalent to:
178	 *   tv.nsec -= NSEC_PER_SEC
179	 *   tv.sec ++;
180	 */
181	if (res.tv.nsec >= NSEC_PER_SEC)
182		res.tv64 += (u32)-NSEC_PER_SEC;
183
184	return res;
185}
186
187/**
188 * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
189 * @kt:		addend
190 * @nsec:	the scalar nsec value to add
191 *
192 * Returns the sum of kt and nsec in ktime_t format
193 */
194extern ktime_t ktime_add_ns(const ktime_t kt, u64 nsec);
195
196/**
197 * timespec_to_ktime - convert a timespec to ktime_t format
198 * @ts:		the timespec variable to convert
199 *
200 * Returns a ktime_t variable with the converted timespec value
201 */
202static inline ktime_t timespec_to_ktime(const struct timespec ts)
203{
204	return (ktime_t) { .tv = { .sec = (s32)ts.tv_sec,
205			   	   .nsec = (s32)ts.tv_nsec } };
206}
207
208/**
209 * timeval_to_ktime - convert a timeval to ktime_t format
210 * @tv:		the timeval variable to convert
211 *
212 * Returns a ktime_t variable with the converted timeval value
213 */
214static inline ktime_t timeval_to_ktime(const struct timeval tv)
215{
216	return (ktime_t) { .tv = { .sec = (s32)tv.tv_sec,
217				   .nsec = (s32)tv.tv_usec * 1000 } };
218}
219
220/**
221 * ktime_to_timespec - convert a ktime_t variable to timespec format
222 * @kt:		the ktime_t variable to convert
223 *
224 * Returns the timespec representation of the ktime value
225 */
226static inline struct timespec ktime_to_timespec(const ktime_t kt)
227{
228	return (struct timespec) { .tv_sec = (time_t) kt.tv.sec,
229				   .tv_nsec = (long) kt.tv.nsec };
230}
231
232/**
233 * ktime_to_timeval - convert a ktime_t variable to timeval format
234 * @kt:		the ktime_t variable to convert
235 *
236 * Returns the timeval representation of the ktime value
237 */
238static inline struct timeval ktime_to_timeval(const ktime_t kt)
239{
240	return (struct timeval) {
241		.tv_sec = (time_t) kt.tv.sec,
242		.tv_usec = (suseconds_t) (kt.tv.nsec / NSEC_PER_USEC) };
243}
244
245/**
246 * ktime_to_ns - convert a ktime_t variable to scalar nanoseconds
247 * @kt:		the ktime_t variable to convert
248 *
249 * Returns the scalar nanoseconds representation of kt
250 */
251static inline u64 ktime_to_ns(const ktime_t kt)
252{
253	return (u64) kt.tv.sec * NSEC_PER_SEC + kt.tv.nsec;
254}
255
256#endif
257
258/*
259 * The resolution of the clocks. The resolution value is returned in
260 * the clock_getres() system call to give application programmers an
261 * idea of the (in)accuracy of timers. Timer values are rounded up to
262 * this resolution values.
263 */
264#define KTIME_REALTIME_RES	(ktime_t){ .tv64 = TICK_NSEC }
265#define KTIME_MONOTONIC_RES	(ktime_t){ .tv64 = TICK_NSEC }
266
267/* Get the monotonic time in timespec format: */
268extern void ktime_get_ts(struct timespec *ts);
269
270/* Get the real (wall-) time in timespec format: */
271#define ktime_get_real_ts(ts)	getnstimeofday(ts)
272
273#endif
274